I am a new user of OpenFOAM and am aiming to use it as part of my Master thesis. I am modelling a floating object under the influence of waves (I will use the groovyBC boundary condition). However I am a little confused as to the difference between the interFoam solver and the interDyMFoam solver.

Could someone please explain the difference between these solvers and for what scenarios they are best used? Is interDyMFoam specifically for use with a dynamic mesh?

Generally, interDymFoam is interFoam plus mesh modification. This mesh modification can either consist of mesh refinement in local areas (e.g. to sharpen the fluid interface, as already said) or of a mesh motion part due to calculated quantities (e.g forces).

If you have to decide which one you need, ask yourself the question if your floating object is moving in the water due to wave forces, or if it is fixed. In case of mesh refinement at the interface: Do you really need it (as it can take quite much computational time), or is a generally (statically) refined mesh in the wave area enough for you...

Thank you for your replies. My floating object is not fixed and I am particularly interested in what happens at the interface, so I guess that leads to using interDyMFoam. Maybe I will try both interFoam and interDyMFoam to compare results.